Alien vs. Predator in the GSMNP

A new breed of predator beetles that could help fight the hemlock wooly adelgid were released in the Great Smoky Mountains National Park two weeks ago.

The hemlock wooly adelgid is a bug from Asia that has invaded the Southern Appalachian Mountains and is rapidly infesting hemlock trees. Without action, the region could lose nearly all of its hemlock trees within five to 10 years, leaving a gaping hole in the forest ecosystem and the landscape.

The insect attacking hemlock trees had no predators and was marching across the region unchecked. In an attempt to lessen the impacts of the hemlock insect, biologists searched Asian forests to find its natural predator. A predator beetle was found that allegedly preys on nothing but hemlock woolly adelgids and should not produce any unexpected side-effects of its own.

Now, a second species of predator beetle has been deployed to help stop the hemlock woolly adelgids. The new predator beetle species is called laricobious nigrinus (pronounced lar-ry-co-be-us ne-guy-nus). A batch of 50 beetles were released on the Tennessee side of the Great Smoky Mountains National Park two weeks ago.

The new beetle species is from the Pacific Northwest and British Columbia. Like the original predator beetle, the new species also eats hemlock woolly adelgid selectively and will presumably die off if it has no more adelgids to eat. The new predator beetle is active in the winter while the original predator beetle didn’t get started until spring.

Biologists believe more than one predator beetle is needed if any hemlocks are to be saved. In Asia, there are several insects that eat the hemlock woolly adelgid and maintain an ecological balance to keep the adelgid from killing hemlocks.

Unfortunately, the hemlock woolly adelgid had already take a strong hold on hemlocks in the region by the time government funding was set aside to address the problem. Even then, funding has not been enough to breed the beetles fast enough. Private groups such as the Jackson-Macon Conservation Alliance and Friends of the Smokies have been raising crucial private funds to help combat hemlock wooly adelgids.

Breeding the predator beetles takes space and money. The two primary beetle breeding labs are at the University of Tennessee Knoxville and Clemson University in South Carolina. The UT lab bred the new species of beetle just released.